It is never explained who Ferb's mother is, or who Phineas and Candace's father is.

As of 2015, it is the longest running Disney animated show, lasting from 2007 to 2015.

It took Creators Dan Povenmire and Jeff 'Swampy' Marsh sixteen years to get this show on television.

Ferb (Thomas Brodie-Sangster) has a crush on Vanessa Doofenshmirtz (Olivia Olson). In Love Actually (2003), Sam (Thomas Brodie-Sangster) learns to play the drums, so that he can impress Joanna (Olivia Olson).

Director and Creator Dan Povenmire, and Director Zac Moncrief left Family Guy (1999) to work on this show.

The first drawing of Phineas was on a piece of butcher's paper, drawn with crayon in a restaurant.

Although Ferb rarely speaks, he has been shown to have a great singing voice.

Phineas and Ferb: Phineas and Ferb: Star Wars (2014) has Ferb's most lines.

Ferb rarely talks. In fact, there are many episodes in which he has no lines at all. (According to Phineas, "Ferb's more of a man of action".)

Sometimes Jeremy works at "Mr. Slushy Burger", and sometimes he works at "Mr. Slushy Dog".

According to Dan Povenmire, Phineas and Ferb's humor style is sort of a hybrid between Family Guy (1999) and SpongeBob SquarePants (1999), two shows that he had worked on.

It is hinted in the series that Dr. Doofenshmirtz could be German, the word "Doof" in his name is German for stupid or idiot.

Each episode contains at least one original song. The writing staff sings the song into the answering machine of Danny Jacob on Fridays to have it be magically written each Monday.

Jaret Reddick, lead singer of the band Bowling for Soup, which does the theme song for this show, is the voice of Danny, lead singer of the fictitious band Love Händle in the series.

Ferb's "large eye" changes depending on what direction he's facing. The large one is always the one furthest away from the screen.

The giant floating baby head, which was first featured in Phineas and Ferb: One Good Scare Ought To Do It!: Parts 1 & 2 (2008), became a running gag in the series. According to Dan Povenmire, the baby head came from "one board panel drawn by Michael Diederich, and one of our directors, Robert Hughes thought it was hilarious, and made a whole bit about it. Now it shows up all the time."

The show takes place in Danville, which is in Jefferson County, which is in the tri-state area. Danville is named after Dan Povenmire, and Jefferson County is named after Jeff 'Swampy' Marsh.

There are one hundred four days in summer vacation, yet the series has one hundred sixty episodes. However it is possible that the winter vacation episodes take place between summers.

Dr. Doofenshmirtz often refers to previous episodes.

While other characters simply call him Perry, Dr. Doofenshmirtz always refers to Perry by his full name (Perry the Platypus). He doesn't abbreviate the names of his other nemeses either (Peter the Panda, Planty the Potted Plant, et cetera).

Major Monogram said "Great Googly Moogly!", which was a quote from Maggie and the Ferocious Beast (1998), Evolution (2001), and a 1957 song by Sid Bradley.

Dr. Doofenshmirtz's robot-man "Norm" was originally a robot to target platypuses. In later episodes, he is seen as his servant.

Dr. Doofenshmirtz name was originally Dr. Meddleshmirtz. Both also have the same number of letters, thirteen.

Candace's best friend Stacy is sisters with Ginger, one of the girls in Isabella's Fireside Girl troop.

Several songs have been re-used, such as Phineas and Ferb's mom's one hit wonder song, that was later played as elevator music, and the Love Händel hit playing on the radio for Dr. Doofensmirtz.

Phineas and Ferb often give relevant facts.

It has been seen in several episodes that Ferb has a crush on Dr. Doofenshmirtz's daughter Vanessa.

Dan Povemire and Jeff "Swampy" Marsh created the show, and voiced Dr. Doofenshmirtz and Major Monogram, respectively.

The family's last names are Flynn and Fletcher.

There's a theory that Doofenshmirtz is the biological father of Candace and Phineas, because both Phineas and Doof has triangular heads, both Candace and Doof have long necks, and there is an episode in which Linda and Doof are seen on a date. If Doof is Candace and Phineas's biological father, then it would be assumed that Doof had an extramarital affair with Linda because Candace and Vanessa are the same age, and Vanessa remembers when her mother and father were married before they divorced.

Phineas and Ferb Get Busted, Phineas and Ferb's Quantum Boogaloo, Wizard of Odd and Ferb TV are the only 4 times there has just been a single plot line revolving around Phineas, Candace and Ferb. Additionally, Road to Danville, This is Your Backstory, Sidetracked and Live and Let Drive are the only 4 times there has just been a single plot line revolving around Perry and Dr. Doofenshmirtz.

Richard O'Brien (of Rocky Horror Picture Show) voices Lawrence Fletcher. In some episodes he, or one of the characters, makes a reference to The Rocky Horror Picture Show.

Phineas is right-handed, as shown when he plays the guitar in "Summer", and uses the baseball bat in Phineas and Ferb the Movie: Across the 2nd Dimension (2011).

Thomas Brodie-Sangster, the person who voiced Ferb, recorded his audio in the UK and sent it to the US. Because Ferb almost never spoke, it wasn't necessary that his voice actor lived near production.

Ran for nearly 8 years.

Dr. Doofenshmirtz's inventions usually end with "inator".

Most of Doofenshmirtz's inventions actually do work, it's just that they're so ridiculous and absurd that they don't actually allow him to take over the Tri-State Area/World.

Dee Bradley Baker (Perry) plays Diogee on Milo Murphy's Law (2016). Additionally, Dan Povenmire and Jeff "Swampy" Marsh also play Dakota and Cavendish on Milo Murphy's Law, as well.

According to Dan Povenmire and Jeff "Swampy" Marsh, Phineas and Ferb and their friends are supposed to be 8 years old. This also aligns with the episode Act Your Age when the kids are choosing where to go to college, which usually takes place between ages 17 and 19.

In the episode Rollercoaster: The Musical, when Candace is showing her mom the rollercoaster, you can see the two Candaces from the future hiding behind a car. Which means, when the future Candace went back to the past, she went back to the day of the roller coaster (the Musical), not the first day of summer.

In the series finale, while the kids are riding Phineas and Ferb's grand finale ride, for a brief moment, they are transformed into versions of themselves that are animated in the style of a traditional Disney character. Then immediately afterwards into photo realistic versions of the actors voicing them. That is, with the exception of Buford, who is not effected at all, and then transformed into an octopus, before all of them are returned to normal.

In season four, episode thirty-three, "Act your Age", Phineas and Isabella kiss ten years in the future, and on the last day of summer, Phineas says he would kiss Isabella in ten years.

Buford owns life-size molds of all his friends (including Candace).

In the series finale, Baljeet is looking at a list of possible coordinates on a GPS device. Although the Northern coordinates are in the correct format, the Western hours are missing. If 00 are substituted for the missing numbers, the majority of the coordinates on the list, would be in Northern Africa.

Candace Flynn and Stacy Hirano are the only regular characters not usually involved in Perry's storylines who have seen him as an agent and didn't have their memory of him erased.

Phineas and Ferb are stepbrothers. Yet, in an episode, they are trying to help their parents celebrate an anniversary by getting Love Händel back together. Considering that Love Händel is meant to be an "80s" band from before the birth of Phineas, Ferb, or Candace, leaves me wondering what the filler should be in this plot hole.